Optical systems engineering is just beginning to come of age. The combination of new metrology, new manufacturing techniques, computer based analytical tools, and the stimulus of several premier optical programs are leading toward a fuller and more complete exploitation of the systems engineering approach to the design, development, fabrication, and operation of high performance optical systems. Systems engineering which involves an integrated interdisciplinary approach to the development of systems is most appropriate for optics. The very high precision character of optics leads to very complex and subtle effects on optical system performance, resulting from structural, thermal dynamical, control system, and even manufacturing and assembly considerations. The systems engineering approach is thus more important to optical system development than most other types of systems. Optical systems are sufficiently unique that communication problems often occur among users, optical engineers, and the rest of the systems team. It is essential that the optics community provide leadership to resolve communication problems and fully formalize the field of optical systems engineering.